Method and apparatus for centrifugal thickening of mixtures and clarifying of liquids



Aprll 3, 1928. 1,664,769

. H. M. CHANCE METHOD AND APPARATUS FOR CENTRIFUGAL THICKENING OF MIXTURES AND CLARIFYING 0F LIQUIDS Filed July 29, 1925 2 Sheets-Sheet 1 lfuienor' April 3, 1928.

H.M.CHANCE METHOD AND APPARATUS FOR CENTRIFUGAL THICKENING OF MIXTURES AND CLARIFYING OF LIQUIDS Flled July 29. 1925 2 Sheets-Sheet 2 raaniea A r. 3; 192's;

' METHOD AND APPARATUS Application filed Jul as, 1925. se rial m. 46,752.

' My invention relatesto the thickening of ore 'pulps 'or other mixtures of liquid and comminuted solids and the partial or complete clarification of a portion of the liquid I constituent of said pulp or mixture bycenor are periodically removed. by cutting ofl the feed and removing the accumulation,

with which they are admixed in the zone of with or Without stopping or slowing down the separator. Centrifugal ore concentrators have been operated in a similar manner.

In. the practice of my invention separation is efiected in a stationary container, of any suitable shape, such as a tank of cylindrical or truncated cone type, the axis of which is preferably, but not necessarily, 4 vertical,

which is provided witln a rotor or. other' means by which arotary motion maybe communicated to any fluid mixture introduced into the said container. The mixture to be thickened preferably, but not necessarily, is introduced at or adjacent to the inner periphery of'the container and acquires a rotary motion from energy transmitted by the rotor, the extreme outer periphery of which' is spaced a suitable distance from the inner periphery of the container, thefannular space thus provided being the locus in which thickening is eflected of the coarser and heavier particles of solid matter, the finer particles being separated from a portion of the liquid highest rotating velocity.at or within the outer boundaries of the rotor.

-Particles of solid matter thrown radially outwardly from the rotor by the centrifugal force'oi rotation, enter a zone adjacent to the walls of the container in which the veloisity of rotation. isreduced by friction with said walls, and thus having their velocity of rotation' reduced, with corresponding reductionin centrifugal force, are free to fall by ,gravity to the lower part of the container, their downward paths of travel being a FOR 'CENTRIFUGAL THICKENING or CLABIFYING or mourns.

inx'ruans Aim .2 v curve approaching a helical or helical spiral type. Y y

The solid material thus thickened by sepa: ration from a largerportion of. the liquid, upon reaching the base of the container may be continuously discharged through adjustably controlled outlets.

(The clarified or partially clarified liquid 1 occupies the space within the outer boundai'rro STATES-[PATENT VYOFFICE.

nnnnrm. CHANGE, OF rnrtazontrnm' rnNnsYLvaNIa.

ries of the rotor, with the most highly clarified liquid in the central and upper portion of said space, from which it may be discharged continuously by gravity, centrifugal force, natural overflow or other means.

An outstanding feature of my invention,' in its most eflicient application, is the intro ductionof the mixture to be separated into the zone in which thickening isbeing elfected, thereby preventing the clarified liquid 00-. cupylng the central and upper zone from becomingadmixed with mixture beingfed into the separator. I do not confine myself to this mode of operation as the mixture may if desired'be introduced through the center to the base of the rotor as is'practiced in centrifugal separators in which the separating vessel 'is the rotating element. In the operat1on of my invention it is, however, essential that the interior of the rotor shall be in free ;communication with the annular space between the'rotor and the walls of'the container.

In the drawings Fig. I is a vertical crosssection and elevation of an apparatus ,in which my invention may be carried out. Fig. II is a cross-sectionatthe line AA v,of Fig. I showing the construction of the rotatingelement and its position with reference to the walls of the vessel. Fig. III is a construction similar-to Fig. I but providing .shown' mounted in bearings 4, 4* bearing 4 being provided with forced Water lubrication controlled by valve 5. The shaft 3 is driven by a pulley 6, and is supported by a thrust ball bearing 7 which carries the weight of the shaft and of the'rotor mounted thereon. The rotor. shown consists of a base- 8, a cylindrical perforate shell 9, reinforcinghoops "10, and impelling and anti-diifu-' s1on vanes 11, which are spaced and held in I 5 position by spacing and anchorage rods 12, part of rotor being braced to the which are attached the valve controlled outlets which furnish the means for dis-r charging clarified liquid. This distributing cone 14 has a cylindrical downward extension which maybe carried down to secure 15 delivery of the mixture at any desired depth in the contain r 1. The thickened mixture is discharged t rough valve controlled outets 16 at or'adja'cent to the hase of the container 1. p L T t The enlarged cross-section shown by Fig;

' I I illustrates the construction of the rotor,

and the relation of; the diffusion vanes 11,

perforate shellj9, spacing bars 12, and reinforcing hoops 10. c

In Fig. III which duplicates many of the details shown by F I, the rotating shaft 3 is apipe or conduit which replaces the yvalve'd outlets 15 of" Fig. I as a' means for discharging the clarified liquid, the discharge through 3' being controlled by the movable sleeve 17 operated by the 'hand lever 19 which covers or unco ers .the ports 18 shown at the base of the ho low shaft .3, In this design the distributing feed cone 14 is connected to and becomes a part of the rotor and i w Qis provided with vertical radial'vanes attached to its upper surface and running with smallclearance below the under surface of the cover of the container; 1'. y

In both of the types illustrated by Figs. I andlII, the feed conduit and hopper 2, 2 V provides for operating the apparatus under any desired hydraulic head or pressure so i that the apparatus is kept full of liquid and mixture, thus excluding 'air from the interior. I It will however be apparent to those.

familiar with the operation of centrifugal separators of other types, that complete en,- closure of'the apparatus is not essential to tures of relatively coarse solids and liquid, where high rotative speed isnot essential to successful performance, the opening in the top may be ofrelatively large diameter, the feed introduced through a central feedpipe discharging near the base of the rotor and the clarifiedv liquid discharged by overflow at the opening in the top of the container 1 I" therefore do not limit myself to the particulaf construction or'arrangements of parts shown bty the drawings, as many other known types o construction can be employe in carrying out my invention as herein de-v 5 scribed and claimed."

The construction of the rotor as shown by successful functioning. In thickening mix- 7 Figs. I and III is a hollow cylindrical cage. with perforate walls and closed bottom, or closedbottom and top, the interior being subdivided by vertical radial vanes. It will be understood" that the interior of the rotor may be subdivided by any suitable means into a series of channels radiating in straight or curved lines towards the periphery, an extreme type of such subdivision being a hon-f ey-comb structure, the object of such'subdivision being to restrain the formation of eddy, currents and counter-flow within the body of therotor. The perforate shell 9 tends to restrain the development .of irregular mass movements within the body of the rotor. If asuflicient number of vanes are used \to restrain such movements, the perforate shell 9 may be eliminated as a struc tural part of the rotor.

Fig. IV is a cross-section of a portion of a rotor illustrating a construction with annular diaphragms 21, which may be perforate as shown, which may be inclined or horizontal, and may be used with or without intersecting vertical vanes similar to '90 those shown by 11 of Fig. I. This drawing also illustrates the use of an inner perforate shell" 9. Attachment to'the shaft 3 is illus trated by the arms and collar 13*".

A ,iguresV, VI and VII illustrate the sub; 95, division of the space within the rotor bya cellular structure shown as of the honeycomb type, each cell diminishing in height from the outer to the inner periphery of the rotor. It will be understood that the cen-v trifugal force will prevent the cells from becoming clogged with sediments when this type of construction is employed. The cells 20 at the larger end are shown by enlarged end view Fig. VI and at "the smaller end by enlarged end view Fig. VII. The cells may be horizontal or inclined. I

The container may be of any suitable form, preferably of cylindrical, truncated f cone or barrel shaped type. The rotor should be adapted to impart rotary motion to that portion of the mixture or liquid in which it is immersed, with minimum disturbance of that portion of the liq-' uid in the annular clearance space between 115 the periphery ofthe rotor and the wall of the container, and with minimum producinsure such free flow or movement of liquid or mixture through the rotorand thus provide the essential free communication between the interior of the rotor and the'space.

external to the rotor, the perforations in shells 9 of Figs. I and II, of 9' of Fig. III, of 9 and 9 of Fig. IV, or of diaphragms such as 21 of Fig. IV, must be large enough to freely pass the largest particles'of the connninuted solids; such perforate shells, diaphragms or the like. being designed for use solely in restraining the formation of eddy currents and erratic mass movements of the fluid mixture. or of the fluid, and are therefore not utilized or utilizable for screening or filtering. Restraint of objectionable movements within the, body of the rotor may be eii'ected by vane-s. diaphragms or partitions of relatively thin material confining the How of mixture or liquid within channels of relatively small cross-sectional area. This will be readily understood by those familiar with centrifugal separators in which both the container and the impelling vanes rotate as a unit.

My invention may be carried out by utilizmg a centrifugal separator, of the types in uid into a clarified or partly clarified liquid,

and a thickened mixture of said liquid and solids, the improved method which consists in imparting substantially uniform angular speed of rotation to a substantially vertical cylindrical body of said fluid mixture; in introducing said mixture to be separated into a region of highrotative speed at a point exterior to but closely adjacent to the peripheral boundary of said rotating body; in causing said solids, by centrifugal force to move away from the center of rotation towards and into a region of relatively slow rotation beyond the peripheral boundary of said rotating body; in causing the said liquid to move towards the center of rotation, whereby the said liquid is clarified and the saidmixture is thickened, and in removing said liquid from the said central region of rotation and the said thickened mixture from said peripheral region.

2. A centrifugal separator comprising in combination a rotor mounted upon a shaft equipped with bearings and means for imparting rotary motion to said shaft, said rotor including a base and a perforate outer wall with perforations larger than the particle-s of solid matter to be separated by said separator, the region of said rotor adjacent to said shaft being in free communication with the region of said rotor adjacent to the inner surface of said perforate wall through channels materially larger than the said particles; a container with walls substantially concentric to said rotor in which said rotor is mounted; a clearance space of substantial width between the outer wall of said rotor and the inner wall of said container; means for feeding the materials .to be separated directly into said clearance space exterior to said rotor; means for removing clarified liquid from said region adjacent to said shaft and means for removing thickened material from the region adjacent to the inner wall of said container.

Signed at Philadelphia, Pa., this 23d day of July, 1925.

HENRY M. CHANCE. 

